Etching apparatus

ABSTRACT

In order to prevent a workpiece from being damaged in etching workpiece of various external diameters, a ceramic holding jig corresponding to the external diameter of workpiece is mounted on a chuck table in a chamber of an etching apparatus. The chuck table is composed of a holding face for holding a workpiece and for converting etching gas into plasma and insulating zones each having an internal diameter smaller than the external diameter of the workpiece and an external diameter larger than the external diameter of the workpiece. In case a workpiece is to be held by either a first ceramic holding jig or a second ceramic holding jig on the chuck table, a jig identifying means installed to the chamber identify in advance which ceramic holding jig is mounted on the chuck table to match the holding jig and the workpiece each other, thereby to prevent the workpiece from being damaged.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an etching apparatus for etching a workpiece by plasma etching.

2. Related Art

A plate-shaped workpiece is ground on its face to a desired thickness by using a grindstone. For example, a semiconductor wafer has a plurality of IC, LSI or the like formed on its surface side and is formed to a desired thickness by grinding its back face.

However, fine cracks called the “microcracks” are generated in the ground face. When a plate-shaped article is divided into individual chips by a later cutting operation, there arises a problem that the folding endurance of the individual chips degrades. Therefore, the ground face is plasma-etched to remove the microcracks (see JP-A-2001-257186, for example).

In the plasma etching apparatus, as disclosed in JP-A-2001-257186, a lower electrode (a chuck table) holds by suction the plate-shaped article to be etched. However, the plate-shaped article may be one of various types with different external diameters. In order that the chuck table may hold the plate-shaped articles stably with sufficient suction force without any leakage of air, therefore, troublesome works are required for replacing the chuck table to match the external diameter of each individual plate-shaped article.

As shown in FIG. 7, therefore, a chuck table 55 is formed into a ring shape by providing its holding face with a plurality of (e.g., two in the shown example) ring-shaped first and second insulating zones 55 d and 55 e having different internal diameters and external diameters. On the other hand, among the various kinds of the plate-shaped articles, ceramic holding jigs 100 and 101 capable of covering those insulating zones and housing plate-shaped articles are produced as many as the plate-shaped articles. These plate-shaped articles are held not by interchanging the chuck tables matching their external diameters but through ceramic holding jigs capable of housing them individually.

In case the plate-shaped articles to be plasma-etched are two kinds of semiconductor wafers having external diameters of 200 mm and 300 mm, for example, the first ring-shaped insulating zone 55 d having an internal diameter of 295 mm and an external diameter of 305 mm and the second ring-shaped insulating zone 55 e having an internal diameter of 195 mm and an external diameter of 205 mm are formed in the chuck table 55 sized to hold a plate-shaped article having an external diameter of 300 mm at the maximum. The semiconductor wafers are housed in the housing portions of the individual holding jigs, by preparing two kinds of holding jigs 100 and 101 having housing portions having external diameters for covering the first insulating zone 55 d and the second insulating zone 55 e and storage portions corresponding to the external diameters of the semiconductor wafers of 200 mm and 300 mm (having internal diameters slightly larger than the external diameters of the semiconductor wafers), and by replacing the holding jig according to the external diameter of the semiconductor wafer to be etched. By thus holding the plate-shaped articles through the holding jigs, the semiconductor wafer of different external diameters can be stably held all over their faces and etched.

SUMMARY OF THE INVENTION

In case, however, the plate-shaped article to be held on the chuck table and the ceramic holding jig mounted on the chuck table do not match each other, for instance if a plate-shaped article having a diameter of 150 mm or 300 mm is delivered onto the chuck table although the ceramic holding jig for the semiconductor wafer having an external diameter of 200 mm is mounted on the chuck table, the plate-shaped article cannot be housed in the ceramic holding jig or even if housed, a large clearance is formed with the inner circumference of the ceramic holding jig. If the plasma etching is performed in that state, there arises a problem that the semiconductor wafer is etched and damaged at its faces other than the back face.

Therefore, the problem to be solved by the invention is to prevent a workpiece from being damaged, by causing the ceramic holding jig to be mounted on a chuck table in a chamber of an etching apparatus and the workpiece to be held on the chuck table to match each other.

In order to solve the above-specified problem, according to the invention, there is provided an etching apparatus comprising: a chuck table for holding a workpiece; etching gas supply means for supplying an etching gas to the workpiece held by said chuck table; a chamber housing said chuck table and said etching gas supply means and having an opening, through which said workpiece is delivered in and out; transfer means for delivering the workpiece into and out of said chamber through said opening; and a shutter for bringing said opening into an opened state or a closed state, wherein said chuck table is configured to include a holding face for holding the workpiece and for converting the etching gas into plasma, and insulating zones each having an internal diameter smaller than the external diameter of the workpiece and an external diameter larger than the external diameter of the workpiece, said insulating zones respectively match at least two types of workpiece with different external diameters, including a first ring-shaped insulating zone having an internal diameter smaller than the external diameter of a first workpiece with the larger external diameter and an external diameter larger than the external diameter of said first workpiece; and a second ring-shaped insulating zone having an internal diameter smaller than the external diameter of the second workpiece with external diameter smaller than said first workpiece, and an external diameter larger than the external diameter of said second workpiece, and said chuck table can mount a first ceramic holding jig for housing said first workpiece and for covering the portion of said first insulating zone of said chuck table that does not contact said first workpiece; and a second ceramic holding jig for housing said second workpiece and for covering the portion of said second insulating zone of said chuck table that does not contact the second workpiece, and further comprising: jig identifying means for identifying said first ceramic holding jig and said second ceramic holding jig.

In case the external diameter of the first ceramic holding jig and the external diameter of the second ceramic holding jig are different, and the jig identifying means is arranged on the outer side of the chamber for measuring the external diameter of the first ceramic holding jig and the external diameter of the second ceramic holding jig when the opening is brought into the opened state, the kind of the ceramic holding jig mounted on the chuck table can be identified from outside the chamber. For example, an optical sensor can be used for the holding discrimination of this case. If the ceramic holding jig is formed to be identified by a feature other than the external diameter, the etching apparatus may be provided with corresponding means for the discrimination.

Moreover, the jig identifying means may have a function to output a signal corresponding to an identified result, and decision means for deciding, by inputting the signal, whether or not the ceramic holding jig mounted on the chuck table matches the workpiece to be delivered into the chamber is connected with the jig identifying means. The transfer means is informed of the result of the decision by the decision means, whereby the transfer means controls the delivery of the workpiece into the chamber. Then, it is possible to avoid the delivery of a workpiece failing to match the ceramic holding jig mounted on the chuck table, into the chamber.

In case the workpiece is a semiconductor wafer, the face of the ground semiconductor wafer is etched in the chamber.

According to the invention, the jig identifying means can determine, before the workpiece is etched, whether the holding mounted in advance on the chuck table is the first ceramic holding jig or the second ceramic holding jig, and the workpiece can be treated according to the identified result.

In case the external diameter of the first ceramic holding jig and the external diameter of the second ceramic holding jig are different, and the jig identifying means is arranged outside the chamber for measuring the external diameter of the first ceramic holding jig and the external diameter of the second ceramic holding jig when the opening is brought into the opened state, the kind of the ceramic holding jig mounted on the chuck table can be identified from outside the chamber. Therefore, the jig identifying means can be kept away from the influences of the etching gas or the plasma.

The jig identifying means has the function to output the signal corresponding to the identified result, the decision means is connected with the jig identifying means, and the transfer means is informed of the result of the decision by the decision means. The transfer means controls the delivery of the workpiece into the chamber on the basis of the decision. Here, the decision means decides for instance whether or not the ceramic holding jig mounted on the chuck table and the workpiece to be inserted match each other. In case the ceramic holding jig mounted on the chuck table and the workpiece to be inserted fail to match each other, the transfer means can stop the delivery of the workpiece into the chamber. It is, therefore, possible to prevent the workpiece from being damaged by the etching.

In case the workpiece is a semiconductor wafer, the semiconductor wafer can be prevented from being damaged, and the microcracks generated by the grinding operation can be etched off. It is, therefore, possible to enhance the folding endurance of the semiconductor chip after dicing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view showing a grinding apparatus and an etching apparatus according to an embodiment of the present invention;

FIG. 2 is a sectional view showing an example of configuration of the etching apparatus;

FIG. 3 is a perspective view showing a chuck table, jig identifying means and ceramic holding jigs in the etching apparatus;

FIGS. 4A and 4B are sectional views showing configurations of the ceramic holding jigs;

FIGS. 5A and 5B are sectional views showing the states, in which the ceramic holding jigs are mounted on the chuck table;

FIG. 6 is a top plan view showing the chuck table and the jig identifying means; and

FIG. 7 is a perspective view showing a chuck table and ceramic holding jigs in the etching apparatus of the prior art.

DETAILED DESCRIPTION OF THE INVENTION

An etching apparatus 50, as shown in FIG. 1, is disposed in the shown embodiment adjacent to a grinding apparatus 10. A workpiece with one face ground by the grinding apparatus 10 is transferred to the etching apparatus 50, in which the ground face can be etched. Here will be described the case in which the back face of a semiconductor wafer as one kind of workpiece is ground in the grinding apparatus 10 and in which microcracks generated on the ground back face of the semiconductor wafer are removed in the etching apparatus 50.

This grinding apparatus 10 is provided with: a cassette 11 for housing a semiconductor wafer W with protective tape adhered to its front surface; a cassette 12 for housing the semiconductor wafer W with protective tape adhered to its front surface and its back surface being ground; transfer means 13 for transferring the semiconductor wafer W out of the cassette 11 or into the cassette 12; a positioning table 14 for positioning the semiconductor wafer W; first and second delivery means 15 and 16 for delivering the semiconductor wafer W; four holding tables 17, 18, 19 and 20 for holding by suction the semiconductor wafer W; a turntable 21 for supporting the holding tables 17, 18, 19 and 20 rotatably; first and second grinding means 22 and 23 for grinding the semiconductor wafer W; and rinsing means 24 for rinsing the semiconductor wafer W ground.

Semiconductor wafers W not yet ground but with protective tape adhered to its front surface are stacked in plural levels in the cassette 11 and are picked up one by one by the transfer means 13 to be placed on the positioning table 14 with their back surfaces directed upward.

After being positioned at a predetermined position in the positioning table 14, moreover, the semiconductor wafer W is attached by suction to the first delivery means 15 and is delivered onto the holding table 17 by the turning motion of the first delivery means 15 to be placed on the holding table 17. At this time, the semiconductor wafer W takes the state in which its back surface is exposed upward.

Next, the turntable 21 turns a predetermined angle (90 degrees in the shown example where there are four holding tables) so that the semiconductor wafer W held on the holding table 17 is positioned just below the first grinding means 22. In this action as well, the holding table 18 is brought to the previous position of holding table 17 before the turn of the turntable 21, the semiconductor wafer to be ground next is delivered out of the cassette 11, and placed on the positioning table. After positioning, the next semiconductor wafer is delivered to the holding table 18 by the first delivery means 15 and placed thereon.

The first grinding means 22 is made vertically movable with respect to an erected wall portion 25. On the inner face of the wall portion 25, there are vertically arranged a pair of rail 26, along which a support plate 28 is driven by a drive source 27 to move vertically along the rails 26. Accordingly, the first grinding means 99 fixed on the support plate 28 is vertically moved.

In the first grinding means 22, a grinding wheel 31 is mounted via a mounter 30 to the leading end of a spindle 29 a rotatably supported. A grinding wheel 32 for a rough grinding operation is fixed below the grinding wheel 31.

When the semiconductor wafer W is positioned just below the first grinding means 22, it is turned by the turning motion of the holding table 17, and the first grinding means 22 is moved downward while the grinding wheel 32 is turned by the turning motion of the spindle 29. The grinding wheel 32 comes into contact with the back face of the semiconductor wafer W so that the back face of the semiconductor wafer W is roughly ground. Here, cut grooves for separating a plurality of circuits are formed in the front surface of the semiconductor wafer W. In the case of so-called “first dicing” in which the back face of the semiconductor wafer is ground till the cut grooves are exposed on their back faces so that the semiconductor wafer is divided into individual semiconductor chips for individual circuits, the rough grinding is ended just before the cut grooves are exposed to the back face.

The semiconductor wafer W thus roughly ground is positioned just below the second grinding means 23 by turning the turntable 21 a specific angle.

The second grinding means 23 is made vertically movable with respect to the erected wall portion 25. On the inner face of the wall portion 25, there are vertically arranged a pair of rail 33, along which a support plate 35 is driven by a drive source 34 to move vertically along the rail 33. Accordingly, the second grinding means 23 fixed on the support plate 35 is vertically moved.

In the second grinding means 23, a grinding wheel 38 is mounted on a mounter 37 which in turn is mounted on the leading end of a spindle 36, which is rotatably supported. A grinding wheel 39 for a finish grinding operation is fixed below the grinding wheel 38.

When the semiconductor wafer W with protective tape 1 adhered to its surface and which has been roughly ground is positioned just below the second grinding means 23, it is turned by the turning motion of the holding table 17, and at the same time the second grinding means 23 is moved downward while the grinding wheel 39 is turned by the turning motion of the spindle 36. The grinding wheel 39 comes into contact with the back face of the semiconductor wafer W so that the back face of the semiconductor wafer W is given a grinding finish. Here in the case of so-called “first dicing”, the cut grooves are exposed to the outside so that the semiconductor wafer W is divided into the individual semiconductor chips.

The semiconductor wafer W given a grinding finish and held on the holding table 17 is positioned near the second delivery means 16 by the turn of the turntable 21. Then, the semiconductor wafer W is delivered to the rinsing means 24 by the second delivery means 16 to be rinsed and cleared of the grinding chips. After this, the semiconductor wafer W is delivered out of the rinsing means 24 by transfer means 40 incorporated in the etching apparatus 50.

The transfer means 40 arranged near the cassette 12 is provided with: a suction unit 41 to suck the semiconductor wafer W; an arm unit 42 for moving the suction unit 41 horizontally and vertically; and a drive unit 43 for driving the arm unit 42. The semiconductor wafer W rinsed is attached by suction to the suction unit 41, and this suction unit 41 moves to deliver the semiconductor wafer W to the etching apparatus 50.

As shown in FIG. 1, this etching apparatus 50 is configured so that a gas supply unit 51 and a plasma treatment unit 52 are connected to each other. The gas supply unit 51 is provided with a tank for reserving an etching gas, a pump for feeding the etching gas to the plasma treatment unit 52, and so on. The tank is stored with a mixed gas whose main components include a fluorine gas such as CF₄ and oxygen.

As shown in FIG. 2, the plasma treatment unit 52 is provided with a chamber 53 for plasma etching, and is configured to house etching gas supply means 54 from the upper side of the chamber 53 and to house a chuck table 55 for holding the workpiece to be etched, from the bottom of the chamber 53. The etching gas supply means 54 introduces the gas supplied from the gas supply unit 51 into the chamber 53.

The etching gas supply means 54 is provided with a spindle 54 a which is made vertically and rotatably movable, fitted in a bearing 56 attached to the chamber 53, and an upper electrode 54 b extending from the lower end of the spindle 54 a. A gas flow passage 57 communicating with the gas supply unit 51 is formed in the etching gas supply means 54, and a plurality of gas injection ports 54 c communicating with the gas flow passage 57 are formed in the upper electrode 54 b.

A lift unit 60 is connected to a side of the spindle 54 a. The lift unit 60 is screwed on a threaded rod 59, which is arranged in the vertical direction. The threaded rod 59 is connected to a motor 58. As the threaded rod 59 is turned by the motor 58, the lift unit 60 moves up and down, and the etching gas supply means 54 accordingly moves up and down.

The chuck table 55 is provided with a spindle 55 a, which is made vertically and rotatably movable, fitted in a bearing 61 attached to the chamber 53, and a lower electrode 55 b extending from the upper end of the spindle 55 a. The lower electrode 55 b is composed of a holding face 55 c made of a metal such as aluminum having a high electric conductivity for holding the workpiece and for converting the etching gas into plasma, and first and second ring-shaped insulating zones 55 d and 55 e. The holding face 55 c is a zone for holding the workpiece by an attractive force. The first and second insulating zones 55 d and 55 e are zones in which the force for holding the workpiece does not act and in which the plasma is not generated by the discharge. In the shown embodiment, the first insulating zone 55 d is formed to protrude upward from the upper face of the outer circumference side, and the first insulating zone 55 d, the second insulating zone 55 e and the holding face 55 c are flush with one another. Alteratively, three or more insulating zones may also be formed.

In the chuck table 55, there are formed a suction passage 63 communicating with a suction source 62, and a cooling passage 65 communicating with a cooling unit 64. The suction passage 63 is branched in the lower electrode 55 b into a plurality of suction ports 63 a and forms the holding face 55 c on the surface of the chuck table 55. The cooling passage 65 cools the held workpiece with the cooling water circulating in the chuck table 55.

In one side of the chamber 53, there is formed an opening 66, through which the workpiece to be etched is delivered in and out. On the outer side of the opening 66, there is arranged a shutter 67 for opening or closing the opening 66 as it moves up and down. This shutter 67 is brought upward and downward by a piston 69, which is driven to move up and down by a cylinder 68. In the bottom of the chamber 53, moreover, there is formed a discharge port 71, which communicates with a gas discharge unit 70 to discharge the used gas from the discharge port 71 to the gas discharge unit 70.

The etching gas supply means 54 and the chuck table 55 are connected with a high-frequency power source 72. This high-frequency power source 72 supplies the etching gas supply means 54 and the chuck table 55 with high-frequency electric power for converting the gas introduced into the chamber 53, into plasma.

As shown in FIG. 3, the first insulating zone 55 d and the second insulating zone 55 e are formed in the chuck table 55. In order to hold two kinds of workpiece having different external diameters, moreover, there are prepared a first ceramic holding jig 100 for the first workpiece having a larger external diameter, and a second ceramic holding jig 101 for the second workpiece having a smaller external diameter. Depending on which workpiece is to be etched, one of the ceramic holding jigs is placed in advance on the chuck table 55 so that the workpiece is held on the chuck table through that ceramic holding jig.

As shown in FIG. 3, the first insulating zone 55 d has internal diameter D₁₁, and an external diameter D₁₂, and the second insulating zone 55 e has an internal diameter D₂₁ and an external diameter D_(22.) With these dimensions, the first workpiece larger in external diameter has an external diameter larger than D₁₁ and smaller than D₁₂, and the second workpiece smaller in external diameter has an external diameter larger than D₂₁ and smaller than D₂₂.

As shown in FIGS. 4A and 4B, the first ceramic holding jig 100 and the second ceramic holding jig 101 are formed to have steps on the inner circumferences so that they have different internal diameters on their front side and their back side. The internal diameter D_(31a) of the front side of the first ceramic holding jig 00 is made slightly larger than the external diameter of the first workpiece so that it can house the first workpiece. The internal diameter D_(41a) of the front side of the second ceramic holding jig 101 is made slightly larger than the external diameter of the second workpiece so that it can house the second workpiece. On the other hand, the internal diameter D_(31b) of the back side of the first ceramic holding jig 100 and the internal diameter D_(41b) of the back side of the second ceramic holding jig 101 are made slightly larger than the external diameter D₁₂ (as referred to FIG. 3) of the first insulating zone 55 d. Thus, the inner circumference of the first ceramic holding jig 100 and the second ceramic holding jig 101 which has the larger internal diameter (on the back side) is fitted and fixed on the outer periphery of the first insulating zone 55 d.

In the shown embodiment, moreover, the external diameter D₃₂ of the first ceramic holding jig 100 and the external diameter D₄₂ of the second ceramic holding jig 101 are made sufficiently different so that the first ceramic holding jig 100 and the second ceramic holding jig 101 can be dearly distinguished.

FIG. 5A shows the case where the first ceramic holding jig 100 is mounted on the chuck table 55 and a first semiconductor wafer W1 as the first workpiece is housed in the first ceramic holding jig 100. FIG. 5B shows the case where the second ceramic holding jig 101 is mounted on the chuck table 55 and a second semiconductor wafer W2 is housed in the second ceramic holding jig 101. In either case, the back faces of the semiconductor wafer W1 or W2 and the ceramic holding jigs 100 or 101 make close contact with the holding face 55 c, thereby preventing air leakage, so that the semiconductor wafer W1 or W2 housed is held by the suction force acting on the holding face 55 c.

On the outer side of the chamber 53, as shown in FIG. 3 and FIG. 6, there is arranged a jig identifying means 80. This jig identifying means 80 has a function to identify the kind of the ceramic holding jig mounted on the chuck table 55, and is provided with an optical sensor 81 in the shown embodiment. The ceramic holding jig, which is mounted on the chuck table 55, has different external diameters according to the external diameter of the semiconductor wafer W housed, so that the optical sensor 81 can identify the kind of the ceramic holding jig on the basis of the distance from the ceramic holding jig.

Failure of the jig identfying means 80 can be prevented through its installation outside the shutter 67 for opening or dosing the opening 66 of the chamber 53. This is because the jig identifying means 80 is thereby not affected by the plasma etching. The holding jig is distinguished when the semiconductor wafer is about to be passed through the shutter 67 in the open state. Therefore, a semiconductor wafer which does not match the ceramic holding jig mounted on the chuck table 55 is prevented from being delivered into the chamber 53 and etched with the plasma.

The jig identifying means 80 has a function to output a signal corresponding to the discrimination result. If a decision means 82 is connected not only with the jig identifying means 80 but also with the transfer means 40, as shown in FIG. 6, the decision means 82 can decide from the signal coming from the jig identifying means 80 whether or not the ceramic holding jig mounted on the chuck table 55 and the semiconductor wafer to be delivered into the chamber 53 match each other. If storage means 83 stores the external diameter of the semiconductor wafer inputted from an operation panel 10 a of the grinding apparatus 10, for example, the decision means 82 is enabled to decide by reading out the value of the external diameter from the storage means 83 whether or not the ceramic holding jig and the semiconductor wafer match each other. In case it is decided that the ceramic holding jig and the semiconductor wafer do not match, moreover, the transfer means 40 is informed of the failure and can control the suction unit 41 and the arm unit 42 so that the delivery of the semiconductor wafer into the chamber 53 is stopped to prevent the semiconductor wafer from being damaged by etching. Here, in case the storage means 83 does not store the external diameter of the semiconductor wafer, the configuration may be so modified that the decision means 82 can recognize the external diameter of the semiconductor wafer. With reference to FIG. 2 and other diagrams, here will be described the case in which the back face of the semiconductor wafer W is plasma-etched after being ground. At first, the shutter 67 is moved down to open the opening 66, and the semiconductor wafer W held by the suction unit 41 (in FIG. 1) is advanced through the opening 66 into the chamber 53. At this time, the kind of the ceramic holding jig mounted on the chuck table 55 in the chamber 53 is identified by the jig identifying means 80 (as referred to FIGS. 3 and 6), and it is decided by the decision means 82 whether or not the semiconductor wafer is to be delivered in. Only when it is decided by the decision means 82 that the semiconductor wafer W to be delivered in matches the ceramic holding jig, the semiconductor wafer W is advanced through the opening 66 into the chamber 53 and put onto the chuck table 55 by suction through the ceramic holding jig by placing the semiconductor wafer on the ceramic holding jig with its back face facing upward and by causing the holding face 55 c to apply suction force.

Next, the suction unit 41 is taken to the outside of the chamber 53, and the shutter 67 is returned to its original position to bring the opening into the closed state. Then, the back face of the semiconductor wafer W is plasma-etched by evacuating the inside of the chamber 53, introducing the gas into the chamber 53 from the etching gas supply means 54, and feeding the high-frequency electric power from the high-frequency power source 72 to the etching gas supply means 54 and the chuck table 55 to convert the introduced gas into plasma. The microcracks are removed by this plasma etching, thereby enhancing the folding endurance of each semiconductor chip.

The semiconductor wafer W plasma-etched its back face as described hereinbefore is attached by suction to the suction unit 41 shown in FIG. 1 after moving down the shutter 67 shown in FIG. 1 and FIG. 2 to open the opening 66, and the suction unit 41 is moved to deliver it out of the chamber 53. Then, the etched semiconductor wafer W is transferred to the rinsing means 24 of the grinding apparatus 10 shown in FIG. 1, in which the semiconductor wafer W is rinsed. After this, the rinsed semiconductor wafer W is housed in the cassette 12 by the transfer means 13. All the semiconductor wafers housed in the cassette 11 are subjected to the grinding operation and the plasma etching described above, and all the semiconductor wafers are housed in the cassette 12.

In the embodiment, the kinds of ceramic holding jigs are identified by the jig identifying means 80 on the basis of the different external diameters of the ceramic holding jigs. However, this discrimination can also be performed on the basis of differences in the shapes, for example. Moreover, the jig identfying means 80 is not be limited to those using the optical sensor.

The invention can be employed in etching for various workpiece having different external diameters. 

1. An etching apparatus comprising: a chuck table for holding a workpiece; etching gas supply means for supplying an etching gas to the workpiece held by said chuck table; a chamber housing said chuck table and said etching gas supply means and having an opening, through which said workpiece is delivered in and out; transfer means for delivering the workpiece into and out of said chamber through said opening; and a shutter for bringing said opening into an opened state or a closed state, wherein said chuck table is configured to include a holding face for holding the workpiece and for converting the etching gas into plasma, and insulating zones each having an internal diameter smaller than the external diameter of the workpiece and an external diameter larger than the external diameter of the workpiece, said insulating zones respectively match at least two types of workpiece with different external diameters, including a first ring-shaped insulating zone having an internal diameter smaller than the external diameter of a first workpiece with the larger external diameter and an external diameter larger than the external diameter of said first workpiece; and a second ring-shaped insulating zone having an internal diameter smaller than the external diameter of the second workpiece with external diameter smaller than said first workpiece, and an external diameter larger than the external diameter of said second workpiece, and said chuck table can mount a first ceramic holding jig for housing said first workpiece and for covering the portion of said first insulating zone of said chuck table that does not contact said first workpiece; and a second ceramic holding jig for housing said second workpiece and for covering the portion of said second insulating zone of said chuck table that does not contact the second workpiece, and further comprising: a jig identifying means for identifying said first ceramic holding jig and said second ceramic holding jig.
 2. An etching apparatus according to claim 1, wherein the external diameter of said first ceramic holding jig and the external diameter of said second ceramic holding jig are different, and said jig identifying means is arranged on the outer side of the chamber for measuring the external diameter of the first ceramic holding jig and the external diameter of the second ceramic holding jig when the opening is brought into the opened state.
 3. An etching apparatus according to claim 2, wherein said jig identifying means has a function to output a signal corresponding to an identified result, and decision means for deciding, by inputting the signal, whether or not the ceramic holding jig mounted on the chuck table matches the workpiece to be delivered into the chamber is connected with the jig identifying means, the transfer means is informed of the result of the decision by the decision means, and the transfer means controls the delivery of the workpiece into the chamber on the basis of the result of the decision.
 4. An etching apparatus according to claim 1, wherein the workpiece is a semiconductor wafer, whereby the face of the ground semiconductor wafer is thereafter etched in the chamber.
 5. An etching apparatus according to claim 2, wherein the workpiece is a semiconductor wafer, whereby the face of the ground semiconductor wafer is thereafter etched in the chamber.
 6. An etching apparatus according to claim 3, wherein the workpiece is a semiconductor wafer, whereby the face of the ground semiconductor wafer is thereafter etched in the chamber. 